Amid anxiety, search continues for missing Malaysia flight

A possible relative cries at the Beijing Airport after news of the missing Malaysia Airlines Boeing 777-200 plane in Beijing on March 8, 2014.

Almost a full day after Malaysian Airlines flight MH370 vanished from the radar en route from Kuala Lumpur to Beijing, officials and aviation experts are at a loss to explain the aircraft's fate.

A six-country search off the Vietnamese coast for the missing Boeing 777-200ER, the 227 passengers and 12 crew on-board yielded nothing so far aside from sighting of an oil slick, which officials in the Malaysian capital confirmed on Sunday.

(Read more: Oil slick hints Malaysian jet may have crashed at sea)

IBM, Freescale Semiconductor employees on flight

Late Saturday, details of individuals on the flight began to emerge, including several tech sector professionals. Freescale Semiconductor said in a statement that 20 of its employees were confirmed passengers. Twelve are from Malaysia and eight are from China.

Meanwhile, a North Texan is one of three Americans aboard the Malaysian jetliner. The family of the missing IBM employee told NBC 5 they received word from the American Embassy that he was on the plane.

Boeing to provide technical assistance

Boeing earlier said it has assembled a technical assistance team to help in the investigations, the aircraft manufacturer said via Twitter.

The search for the missing passenger jet will go on "round the clock," Royal Malaysian Air Force Operations & Exercise Director Brigadier General Affendi Buang told reporters on Saturday.

Still, no wreckage from MH370 has yet been recovered, and the probable cause of the aircraft's disappearance is far from being determined. It's "too early to make any conclusive remarks," Malaysian Prime Minister Najib Razak said on Saturday, and authorities are "investigating all possibilities."

Terror concerns

Rumors of the plane landing safely in China—later found to be erroneous—and rumors of a hijack or terrorist bombing have only compounded the agony of families and relatives of the passengers on MH370. Reuters reported at least two people on board may have been carrying stolen passports.

"Families are struggling for answers and no one can give them any," wrote Stephen Forshaw, former vice-president of Public Affairs at Singapore Airlines (SIA) said in an entry on his Facebook page on Saturday. "It could be a long time before the answers are all found."

Forshaw added: "We have to prepare for the worst possible news, hope and pray for survivors, support those whose loved ones are affected, and above all, be patient and put our faith in those who have the most difficult and grim task of finding and investigating this tragedy."

Malaysia Airlines loses contact with plane

CNBC's Bertha Coombs reports Malaysia Airlines has lost contact with one of its planes carrying 239 people.

Under a barrage of unrelenting questions about the likely scenarios—including terrorism—that may have caused air traffic controllers to lose contact with the flight, a visibly emotional Malaysia Airlines CEO Ahmad Jauhari Yahya urged the media not to jump to conclusions. "We seem to be living by speculation now," he said at a late-evening press conference on Saturday. "We are not ruling out anything."

Aviation experts contacted by CNBC were perplexed about the likely cause and were reluctant to speculate. "At the moment, its a mystery," Andrew Herdman, director general of Association of Asia Pacific Airlines (AAPA) in Kuala Lumpur. There are "almost no clues on what happened. It's an extremely unusual event."

No weather issues in Southeast Asia

The 11-year-old Boeing, powered by Rolls-Royce Trent engines, took off at 12:40 a.m. (1640 GMT Friday) from Kuala Lumpur International Airport and was apparently flying in good weather conditions when it went missing without a distress call, Reuters reported.

There are no significant weather conditions in the area, "pretty much clear skies" from Kuala Lampur all the way up to Vietnam and Southeast Asia, according to Michael Palmer, meteorologist on duty at The Weather Channel.

The association's Herdman said the absence of any signal from the flight's Emergency Location Transmitter was "curious" as the device would emit a signal triggered automatically in the event of an accident which would be picked up by aircraft in the vicinity or by air traffic controllers. "It's an issue if it didn't go off."

ChinaFotoPress| Getty Images

The arrival board shows Malaysia Airlines Flight MH 370 delayed at the Beijing Capital International Airport on March 8, 2014.

The flight last had contact with air traffic controllers 120 nautical miles off the east coast of the Malaysian town of Kota Bharu, Malaysia Airlines chief executive said in a statement. The airline said people from 14 nationalities were among the 227 passengers, including at least 152 Chinese, 38 Malaysians, seven Indonesians, six Australians, five Indians and four French.

"It's very difficult to speculate but the fact that communication was shut off suddenly points to some catastrophic event," Herdman said. "You'd get some warning" in the event of a mechanical failure, he explained.

Memories of 2009 Air France flight

Ominously, some observers are drawing parallels with an Air France flight that crashed into the South Atlantic on June 1, 2009, killing all 228 people on board. It vanished for hours and wreckage was found only two days later.

"In the case of Air France 447 in 2009, it took over a year to find the plane, and it was in ocean over 5 km deep,"wrote Forshaw in his Facebook post. "I'm sure this won't be as complex but I make the point that our natural desire to know what happened maybe hard to fulfill," the former Singapore Airlines chief spokesman said.